Network and method of realizing local roaming for subscribers

ABSTRACT

A network for implementing localized roaming of mobile subscribers includes: a base transceiver station, a base station controller, a Mobile Switching Center (MSC), a Visiting Location Register (VLR) and a Home Location Register (HLR), and at least one Roaming Number Manager (RNM); wherein said RNM, connected with the HLR in the home network and an MSC/VLR in a contracted roaming network, and manages mobile phone numbers in the home network and local mobile phone numbers in the contracted roaming network, takes collection of the local mobile phone numbers in the contracted roaming network as a resource pool, and allocates the mobile phone numbers in the contracted roaming network to subscribers roaming in the contracted roaming network dynamically through the MSC/VLR in the contracted roaming network.

FIELD OF THE INVENTION

The present invention relates to a mobile communication network as wellas a method for implementing roaming of mobile subscribers.

BACKGROUND OF THE INVENTION

In the traditional mobile phone roaming procedure, communication linkshave to be established between the mobile networks both in the homeregion and in the roaming region to support calls of mobile subscribersin roaming state and to enable mobile subscribers in roaming state touse diverse telecom services, such as initiating calls or answeringcalls, etc. However, since communication route is long and more networkresources are consumed in roaming state, the service cost in roamingstate is higher than that in normal state. Especially, in internationalroaming state, any call to the subscriber is international toll call,i.e., the call has to be accomplished through the voice path between themobile network in the home country and that in the roaming country;therefore, the roaming subscriber has to pay the international toll costfrom the home country to the roaming country; even though the caller iswithin a stone's throw to the roaming subscriber (e.g., when two membersin a tourist party are calling in a roam region), both parties have topay the toll for international call. As a result, the communicationdemand of roaming subscribers is suppressed by the expensive cost.Therefore, people are eager to implement localized roaming of mobilephones to decrease expensive roaming call cost.

However, the traditional mobile networks can't meet such a demand. Thestructure of a typical traditional mobile network is shown in FIG. 1. Asshown in the network in home country in FIG. 1, the network entitiesrelated to mobile phone roaming processing in a traditional networkinclude a Base Transceiver Station (BTS), a Base Station Controller(BSC), a Mobile Switching Center (MSC), a Visiting Location Register(VLR) and a Home Location Register (HLR). For example, when thesubscriber's mobile phone is roaming in different countries, the mobilephone has to use its number N in the home country wherever it is becausethe number of the mobile phone N is stored in the HLR of thesubscriber's home network. A call to the roaming subscriber has to beswitched to the home country of the subscriber, so that the MSC in thesubscriber's home country can query HLR in the home country about theroute and establish the voice path to the roaming country. However, inmany cases, this is unnecessary; for example, when the caller is in theroaming country where the called subscriber is or a call is initiatedfrom the third country except for the home country or the roamingcountry where the called subscriber is. Even though it is unnecessary,the roaming subscriber has to bear the charge for international tollcall from the home country to the roaming country.

The reason for above case lies in the process to called number by theswitching device. An international call is first routed to a gatewayoffice in the called subscriber's home country, herein a furtherdetermination for the called number's property; if it is a mobile phonenumber, the call is routed to GMSC in the mobile network for subsequentprocess. Each country has its independent numbering scheme, so switchingdevices in one country cannot determine number properties of othercountries, i.e., the called is a telephone or mobile phone, because thisrequires a large quantity of configuration data, and it is moreimportant that change of numbering scheme in each country will affectother countries, and this will cause numbering schemes in countries lackof independence.

For solving said problem, the mobile subscriber can use a local numberin a roaming region/network. Viewed from the point of the roamingregion/network, some local mobile phone numbers are allocated forforeign subscribers roaming in the region/network. And the roamingsubscriber can share local services using the local number.

SUMMARY OF THE INVENTION

To solve above problem, the present invention provides a network forimplementing localized roaming of mobile subscribers and a method forimplementing localized roaming network, localized roaming of mobilesubscribers can be implemented at lower cost and with lower networkresource occupation through the network and method provided by thepresent invention.

To implement localized roaming service, the network for implementinglocalized roaming of mobile subscribers includes: a base transceiverstation, a base station controller, a Mobile Switching Center (MSC), aVisiting Location Register (VLR) and a Home Location Register (HLR), andat least one Roaming Number Manager (RNM);

Wherein the RNM, connected with the HLR in the home network and anMSC/VLR in a contracted roaming network, and manages mobile phonenumbers in the home network and local mobile phone numbers in thecontracted roaming network, takes collection of the local mobile phonenumbers in the contracted roaming network as a resource pool, andallocates the mobile phone numbers in the contracted roaming network tosubscribers roaming in the contracted roaming network dynamicallythrough the MSC/VLR in the contracted roaming network.

The Roaming Number Manager (RNM) may be embedded in the HLR.

The method for implementing localized roaming of mobile subscribersbased on the network includes:

a. configuring the RNM with local mobile phone numbers in the contractedroaming network, an independent Public Switched TelephoneNetwork/Integrated Service Digital Network (PSTN/ISDN) number and asignaling point code;

b. configuring data in entities of the contracted roaming network andentities of the home network, so that the subscriber location querymessage taking a local number in the roaming network as the destinationaddress will be directed to the RNM in the home network;

c. establishing interfaces between the RNM and entities of thecontracted roaming network as well as between the RNM and entities ofthe home network;

d. developing communication services in the roaming network based on theconfiguration in respective entities of the contracted roaming networkand the home network, implementing localized roaming of the subscriber.

The step c includes:

c1. establishing an interface between the RNM and an MSC in the roamingnetwork;

c2. establishing an interface between the RNM and the HLR in the homenetwork.

The step d includes a subscriber location update process:

d1. sending a location update request from the VLR currently serving thesubscriber to the HLR in the home network;

d2. according to the location update request received from the VLR andthe current location of the subscriber, addressing the RNM correspondingto the current location of the subscriber through the PSTN/ISDN numberof RNM and informing the RNM of the subscriber location update, by theHLR in the home network;

d3. allocating by the RNM a local mobile phone number in the roamingnetwork, to the subscriber, and returning said number to the HLR in thehome network;

d4. inserting said local mobile phone number in the roaming network intothe VLR currently serving the subscriber, and returning anacknowledgement message of obtaining said number in the roaming networkto the RNM, by the HLR in the home network.

The step d3, before allocating a local mobile phone number to thesubscriber, further includes: determining by the RNM whether the roamingregion where the subscriber is roaming is a contracted roaming region;if so, allocating one from the available numbers in the contractedroaming network and feeding the allocated number back to HLR in the homenetwork by the RNM; otherwise feeding the mobile phone number of thesubscriber in the home network to HLR in the home network.

An incoming call or an outgoing call is processed by using the numberfed back from RNM in the home network.

The call is processed by using the number fed back from RNM in the homenetwork in the following manner: when acting as the caller, thesubscriber uses the number fed back from the RNM in the home network toinitiate a call; when the subscriber acts as the called party, if thecalled number is the mobile phone number in home network, the MSC in thehome network queries HLR in the home network to determine the callingroute, the HLR finds the corresponding subscriber record, obtainsaddress of VLR currently serving the subscriber, and accesses the VLR toobtain the calling route, with which the HLR instructs the MSC in thehome network to establish a calling route; if the called number is alocal mobile phone number in a roaming region, the MSC in the roamingnetwork queries RNM about calling route, the RNM finds the subscriberidentifier, queries the HLR about the calling route in accordance withthe subscriber identifier, and forwards the calling route returned fromHLR to the MSC in the roaming network.

The method further includes: when the subscriber leaves the contractedroaming network, the HLR in the home network informs the RNM of thesubscriber location update, the RNM releases the local mobile phonenumber, occupied by the subscriber, in the roaming network, and breaksthe mapping between the number and the subscriber.

The VLR in step d1 addresses the HLR in the home network in accordancewith International Mobile Subscriber Identifier (IMSI) of thesubscriber.

The information carried in the location update request sent from VLR toHLR in step d1 and the parameters carried in the location updateinformed from HLR to RNM in step d2 include: the IMSI of the subscriberand/or the mobile phone number in the home network, current location ofthe subscriber and old location of the subscriber.

Since a RNM is configured in the network provided by the presentinvention, a local mobile phone number in the roaming region can beallocated to the subscriber through the RNM according to the mobilesubscriber's roaming region, and the number is released when thesubscriber leaves the roaming region; therefore the subscriber can usethe number in its roaming region during roaming to initiate calls oranswer calls and thus enjoy localized roaming service, for example, thesubscriber needn't to pay the charge for international long distancecall when he/she answers the call; such a network can reduce networkresource occupation when mobile subscribers communicate in roamingstate, and reduces greatly subscribers' communication cost in roamingstate; for operators, the network according to the present invention canprovide a new localized roaming service and can extend services to otherregions or countries to exploit new markets, attract subscribers,improve subscriber's loyalty, and encourage subscribers to use mobilephones in roaming state; in addition, the present invention requireslittle modification to traditional mobile networks, low cost andconvenient implementation.

In the method according to the present invention, since reasonableaddressing for RNM as well as respective communication processing, theHLR can obtain services from different RNMs according to thesubscriber's roaming region, and a single RNM can provide services for aplurality of HLRs; thereby the flexibility of network structure isenhanced, and utilization rate of numbers in the roaming region isimproved; the interfacing between mobile communication network devicesis simplified; the impact of implementation of localized roaming totraditional mobile communication networks is reduced, i.e., RNMs shouldbe introduced into traditional mobile networks to implement localizedroaming with minimum impact.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the structural diagram of a traditional cellular mobilecommunication network;

FIG. 2 is the structural diagram of the cellular mobile phone networkaccording to the first embodiment of the network of the presentinvention;

FIG. 3 is the structural diagram of the cellular mobile phone networkaccording to the second embodiment of the network of the presentinvention;

FIG. 4 is a suggested data structure employed in the network of thepresent invention;

FIG. 5 is the structural diagram of the cellular mobile phone networkaccording to the third embodiment of the network of the presentinvention;

FIG. 6 is the flow diagram of the first embodiment implemented with themethod according to the present invention;

FIG. 7 is the roaming subscriber location update signaling flow used inthe present invention;

FIG. 8 is a signaling flow used in the present invention, through whichthe roaming subscriber is called by means of his/her number in theroaming region;

FIG. 9 is a signaling flow used in the present invention, through whicha short message is sent to the subscriber by means of his/her number inthe roaming region;

FIG. 10 is a signaling flow used in the present invention, through whichthe roaming subscriber is called by means of his/her mobile phone numberin the home region;

FIG. 11 is the flow diagram of the second embodiment of the method ofthe present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The localized roaming described in the present invention refers to thatthe subscriber's mobile phone in roaming state obtains a local number inthe roaming region and initiates calls or answer calls with the number,so that the subscriber can utilize network resource in the roamingregion and enjoy localized services, similar to a local subscriber inthe roaming region, and thus avoiding unnecessary voice path detour andreducing communication cost in roaming state.

In the implementation of localized roaming of mobile phones according tothe network provided by the present invention, a mobile phone(subscriber) when roaming is automatically allocated with a local mobilephone number in the roaming region by its home network if the roamingregion is a contracted roaming region (which has reached some agreementwith the home operator). When the subscriber leaves the contractedroaming region, the home network releases the temporary number used bythe subscriber. In the contracted roaming region, the subscriber usesthe local number to initiate calls or answer calls and enjoy localizedroaming service. For example, when the subscriber is roaming in aroaming country, the subscriber needn't to pay the charge forinternational toll calls when he/she answers calls; thus thecommunication cost in roaming state is reduced greatly.

The present invention will be described in further detail taking theroaming across countries as an example, with reference to the attacheddrawings.

FIG. 2 is the structural diagram of the cellular mobile phone networksaccording to embodiment 1 of the present invention. As shown in FIG. 2,there are 3 networks. The network entities according to the presentinvention refer to the home network, which comprises: a Base TransceiverStation (BTS) 1, a Base Station Controller (BSC) 2, a Mobile SwitchingCenter (MSC) 3, a Visiting Location Register (VLR) 4 and a Home LocationRegister (HLR) 5, and a Roaming Number Manager (RNM) 6 connected withHLR 5;

The RNM 6 is a network entity, which is used to manage mobile phonenumbers in the contracted roaming country; the RNM takes the collectionof obtained mobile phone numbers in the contracted roaming country as aresource pool, and allocates the mobile phone numbers in the contractedroaming country to roaming subscribers dynamically; furthermore, RNM isalso used to:

(1) store mobile phone numbers in the contracted roaming country;

(2) determine the current default phone number of the subscriber. Whenthe subscriber roams to the contracted roaming country, the RNMallocates a mobile phone number from the available numbers in thecontracted roaming country to the subscriber as the current defaultphone number of the subscriber in the roaming country, and stores themapping between the subscriber and the number; otherwise RNM designatesthe subscriber's mobile phone number in the home country as the currentdefault phone number of the subscriber in the roaming country;

(3) release the local phone number in the contracted roaming countrywhich is allocated to the subscriber. When the mobile phone subscriberleaves the contracted roaming country and registers his/her location inanother country, the HLR in the home country inform the RNM in the homecountry of the subscriber's location update to indicate that thesubscriber has moved out of the country; in this case, RNM releases thelocal mobile phone number occupied by the subscriber and break themapping between the number and the subscriber. The time span fromallocation of the number to releasing is called the life time of thenumber;

(4) take an appropriate policy to reuse the released local number in thecontracted roaming country. To avoid any possible subscriber numberconflict in the dynamic allocation process, RNM reuses released numberswith certain anti-conflict policies or combinations of policies. Asimple but practicable policy is: the released number is lockedtemporarily within a certain time period, which is proportional to thelife time of the number; after the time period, the number may bereallocated to a roaming subscriber. RNM stores and exercises abovepolicies.

(5) bind a number in the contracted roaming country to the subscriber.According to the demand of mobile phone subscriber, a number in thecontracted roaming country is bound to the subscriber for a long term,and the number can't be allocated to any other roaming subscriber. Evenif the subscriber is not in the roaming country, the mapping between thenumber and the subscriber is still maintained. Above operation is callednumber binding, and the binding relation is stored in the RNM in thehome country.

If the network shown in FIG. 2 is used, the operator deliveringlocalized roaming service requires obtaining mobile phone numbers insome roaming countries for the roaming service; those countries arecalled contracted roaming countries, and the amount of the requiredphone numbers in a contracted roaming country relates to the number ofsubscribers roaming in that country. The more the roaming subscribersare, the more the required phone numbers are. As shown in FIG. 2, in thehome country, the subscriber uses number N; in the contracted roamingcountry A, he/she uses a local mobile phone number N1; in thenon-contracted roaming country B, he/she still use the mobile phonenumber N in the home country.

In the cellular mobile communication network in the embodiment shown inFIG. 2, the Base Transceiver Station (BTS) 1 is a device that transmitsor receives radio signals and serves a certain area and establishesradio connections with mobile phone in the area; the BTS 1 is connectedto the Base Station Controller (BSC) 2, which manages radio resource andcontrols the operation of BTS 1; the Mobile Switching Center (MSC) 3 ismainly designed to control mobile call process; the Visiting LocationRegister (VLR) 4 is designed to store the data of mobile phonesubscribers that are roaming in the region dominated by it. All of abovedevices are standard ones in a mobile communication network. The HLR,VLR, MSC, and RNM cooperate with each other to manage mobilesubscribers.

Hereunder the network provided by the present invention and RNM arefurther described with the interaction between RNM and HLR in the mobilephone location update and route query process:

In the network shown in FIG. 2, first, the home country where the mobilephone obtains some mobile phone numbers in the contracted roamingcountry; when a mobile phone is roaming into the contracted roamingcountry, it registers its location at the local VLR through BTS, BSC andMSC; the VLR initiates a location update request to the subscriber'sHLR. The HLR determines the location change of the subscriber's mobilephone; the HLR informs RNM that the subscriber's location has changedand requests to allocate a mobile phone number in the roaming country tothe subscriber's mobile phone. The RNM determines if the subscriber isin a contracted roaming country; if the subscriber is in a contractedroaming country and is the first entry (no local number has beenallocated to the subscriber) into the country, the RNM allocates anumber from the available mobile phone numbers in the contracted roamingcountry and feeds the number back to HLR, and stores the mapping betweenthe number and the subscriber (the mapping may involve multiple numbers,such as the number in the home country, the temporary local number inthe roaming region, and bound numbers); if not, the RNM feeds the numberin the subscriber's home country back to HLR. The above number fed backby RNM to HLR is called the current default number of the subscriber.The HLR inserts the current default number of the subscriber fed back bythe RNM in the home country and other data in the VLR of the currentregion where the subscriber is, deletes the subscriber record in theoriginal VLR, updates the mobile phone location information in thesubscriber record, and informs the subscriber of the current defaultphone number; if the current default phone number doesn't change, thenotification procedure may be omitted. In FIG. 2, when the subscriberroams from the home country into the contracted roaming country A, theHLR in the home country allocates a local mobile phone number N1 in theroaming country to the subscriber, and inserts number N1 and other dataof the subscriber in the VLR in country A where the subscriber iscurrently, deletes the subscriber record in the VLR in home country, andinforms the subscriber of the current default phone number N1; if thesubscriber roams into the non-contracted roaming country B, the RNMinstructs to use the mobile phone number N in the home country; the HLRin the home country inserts number N and other data of the subscriber(e.g., contract data) in the VLR in country B the subscriber is.

When the subscriber answers an incoming call or initiates an outgoingcall in the contracted roaming country, the subscriber's mobile phoneuses the mobile phone number in the current roaming country to processthe call. That is to say, when the mobile phone of the roamingsubscriber serves as a caller, it uses the temporary number allocated byRNM (i.e., the current default mobile phone number of the subscriber) toinitiate the call; when it is a called, the caller may dial the localmobile phone number in the roaming country or the mobile phone number inthe home country, and the MSC in the roaming country (if the callerdials the number in the roaming country) queries RNM about the callingroute or the MSC in the home country (if the caller dials the number inthe home country) queries the HLR in the home country about the callingroute; in the former case, RNM finds the subscriber identifier accordingto the called number in roaming country, and then queries HLR about theroute. The HLR finds the corresponding subscriber record and obtainssubscriber location information (i.e., VLR number in the current roamingcountry), and thus obtains the routing information through accessing theVLR in the roaming country, and then instructs the MSC to establish thecall. In the RNM in the home country, if any number maps to asubscriber, the mapping is unique; however, a subscriber may correspondto numbers in different countries; no matter which number is dialed bythe caller, HLR can find the unique subscriber record and thus obtainthe subscriber location information. In FIG. 2, when the subscriberroams into country A, the calling subscriber who calls the roamingsubscriber may dial either number N or N1.

Only when the country after subscriber location update varies, theaction of allocating a mobile phone number in the roaming country willbe triggered. As long as the subscriber stays in the country, abovenumber will be used, until the subscriber's mobile phone registers itslocation in another network. After above phone number allocation processis finished, the network will inform the roaming subscriber of thetemporary number in the local roaming country in some ways: shortmessage, voice or Unstructured Supplementary Service Data (USSD) arepossible ways to be used, depending on the capability of the network andthe operator's choice.

When the mobile phone subscriber leaves the contracted roaming countryand enters into another country, the HLR in the home country will informthe RNM of the subscriber location update (i.e., the subscriber leavesthe country), RNM will release the local mobile phone number occupied bythe subscriber and break the mapping between the number and thesubscriber. The time span from allocation to releasing is called thelife time of the number. For example, as shown in FIG. 2, when theroaming subscriber leaves country A, RNM will releases number N1.

In addition, to avoid any possible conflict between subscriber numbersduring dynamic allocation, certain anti-conflict policies may be used toreuse the released numbers. In this embodiment, the policy is: thereleased number is locked (unavailable) temporarily within a certaintime period, which is proportional to the life time of the number; afterthat time period, the number may be reallocated to another roamingsubscriber.

If a mobile phone subscriber frequently travels between the home countryand a contracted roaming country and requires to possess a number in thecontracted roaming country for a long term, a number may be allocated tothe subscriber from the available numbers in the contracted roamingcountry as a fixed number, which will not be allocated to any otherroaming subscriber; even though the subscriber leaves the contractedroaming country, the mapping between the number and the subscriber isstill maintained. Above operation is called number binding. When thesubscriber roams into above contracted roaming country, the HLR in thehome country is triggered by a location update request to request theRNM to allocate a local mobile phone number to the subscriber, RNM willreturn the bound number to HLR, so that the subscriber is enabled to usethe bound number to process calls. When the subscriber doesn't need thebound number any more, the binding may be broken, and the number will bereleased and reused. Certainly, numbers in multiple contracted roamingcountries may be bound to a subscriber.

When the caller dials a bound number of the called subscriber, the RNMwill find the subscriber corresponding to the number through query, findthe subscribers record, and obtain the subscriber's location information(VLR number) via HLR, to accomplish route query. Therefore, if thecalled subscriber has a bound number, the caller will have more choices:the called subscriber's number in the home country, the bound numbers,or the number in the current contracted roaming country.

FIG. 3 shows a preferred embodiment 2 according to the presentinvention, wherein RNM is integrated into HLR as a module. In theembodiment 2, the HLR is enhanced in functionality: it not only storessubscriber data (including subscriber identification number, currentdefault mobile phone number, type of contracted service, currentlocation (VLR number, MSC number), etc.) but also delivers the followingfunctions: managing mobile phone numbers obtained from the contractedroaming countries, allocating temporary mobile phone numbers in theroaming countries to roaming subscribers, and storing mapping betweensubscribers and numbers, and release the temporary numbers used by thesubscribers when subscribers leaves the contracted roaming countries.

FIG. 4 is a suggested data structure employed in the network of thepresent invention.

The data structure shown in FIG. 4 comprises three tables including acountry index table, a local mobile phone number table and a subscriberrecord table. Herein, the country index table lists home countries,contracted roaming countries and entry addresses of the local mobilephone number table corresponding to these countries, through which thelocal mobile number table of the contracted roaming countries and thehome countries can be found, countries not listed in the table arenon-contracted roaming countries; the local mobile phone number tablestores the mobile phone numbers allocated by the contracted country andtheir status in a country; the subscriber record table stores subscriberdata, e.g., subscriber location information, subscriber subscriptioninformation. In the conventional network, the subscriber record tablecan be found in HLR.

In the conventional network, a subscriber have only the mobile phonenumber in the home country, the HLR obtains subscriber locationinformation through looking up the subscriber record table according tothe mobile phone number in the home country; according to the presentinvention, a subscriber may have more than one mobile phone numbers indifferent regions/networks: a number in the currently roaming region, anumber in the home country and bound numbers in contracted roamingcountries if any. The subscriber location information can be foundaccording to any one of above numbers, and thus routing information isobtained. The procedure in which subscriber location information isqueried according to the subscriber's number in roaming region or thebounds number in contracted roaming country is shown in FIG. 4.

A subscriber which has a number NH in the home country is roaming incontracted roaming country A, and the subscriber is allocated for alocal mobile phone number NA2.

1. querying for the country code contained in called number in countryindex table, and obtaining the entry address of local phone number tableof the corresponding roaming country;

2. obtaining the subscriber identifier through querying about NA2 in thelocal mobile phone number table in contracted roaming country A;

3. querying about the subscriber identifier in the local phone numbertable of home country, and obtaining the subscriber's mobile phonenumber in its home country;

4. querying about the subscriber identifier in subscriber record table,finding subscriber record corresponding to the subscriber, and obtainingthe location information; the steps 1-3 are implemented in RNM, and step4 is implemented in HLR.

If the RNM is integrated in HLR, step 3 can be omitted after step 2, andsubscriber location information is obtained through directly queryingabout subscriber identifier in the subscriber record table. This isshown in FIG. 4.

In the method according to the present invention, the operator thatprovides localized roaming service needs to obtain the numbers incertain roaming regions/networks for roaming service; these numbers arecalled contracted numbers, and the regions/networks that provide thesenumbers are called contracted roaming regions/networks. For contractednumbers, their physical home region/network is the contracted roamingregion/network; whereas their logical home region/network is theoriginal home network where the localized roaming service is provided.

To implement localized roaming service, new functional entities—RNM isintroduced in traditional cellular mobile communication networks. A RNMmay manage mobile phone numbers in different regions/networks; whereasthe mobile phone numbers in different regions/networks may be managed bydifferent RNMs, i.e., a RNM can provide service for a plurality of HLRs,and a HLR can obtain service from different RNMs, depending on thesubscriber's roaming region.

FIG. 5 is the third embodiment of the present invention. FIG. 5 showsthe connections between network structures and entities related with thepresent invention. There are 3 networks in the figure: a network in thesubscriber's home country, a network in the contracted roaming country Aand a network in the contracted roaming country B; wherein the cellularmobile network in the home country comprises two HLRs (HLR(a) andHLR(b)) and two RNMs (RNM(a) and RNM(b)). The RNM(a) and RNM(b) managelocal mobile phone numbers provided from the networks in contractedroaming country A and B, respectively.

It should be noted that the entities in the figure are not all entitiesof the network.

It is seen from FIG. 5 that the structure of the cellular mobilecommunication network that implements localized roaming service is veryflexible; there may be a plurality of RNMs and HLRs in the network; aRNM can provide service for a plurality of HLRs, so contracted numberscan be shared by subscribers of these HLRs and usage efficiency ofcontracted number is improved; a HLR can obtain service from differentRNMs, depending on the subscriber's roaming region, in such anarrangement, numbers from a contracted roaming country are managed in aconcentrated manner (the same RNM) and addressing is simplified.

Taking the Global System for Mobile Communications (GSM) as an example,the method for implementing localized roaming for subscribers in mobilecommunication system according to the present invention, referring toFIG. 6, the method comprises:

Step 1: allocating independent PSTN/ISDN number and independentsignaling point code, so that RNM can be addressed in the telephonesignaling network;

The step doesn't change the addressing for traditional entities in thecellular mobile communication network;

Step 2: configuring appropriate data in the contracted roamingregion/network and the home network, so that the subscriber locationquery message taking the local number in the subscriber's roamingregion/network as the destination address will be directed to RNM in thesubscriber's home network;

For any call to a contracted number, a query about location of thecalled mobile phone subscriber will be made to the RNM in the logicalhome region/network serving the contracted number, taking the contractednumber as the destination address. A signaling path from the routingquery initiating entity to the RNM is configured, and routing data atthe network nodes in the signaling path is configured, so that thesignaling message taking the contracted number as the destinationaddress is routed correctly to RNM through the nodes in both the roamingregion/network and the home network.

Usually, subscriber location queries are often initiated from a GMSC inthe physical home network of the called number. If the caller is asubscriber in a PSTN, and the network capability is available, the querymay be initiated from any signaling point that supports MobileApplication Part (MAP), e.g., local exchanger, international tandemexchange center for outgoing calls, etc.

Step 3: establishing interfaces between RNM and relevant devices,including:

(1) Interface Between RNM and MSC

A GMSC/SMS GMSC (Gateway Mobile Switching Center/Short Message ServiceGateway Mobile Switching Center) queries about routing information ofthe called subscriber in RNM, to accomplish call establishment anddistribution of short messages.

The interface employs MAP (Mobile Application Part), which correspondsto the signaling between GMSC and HLR.

(2) Interface Between RNM and HLR

This interface is used to exchange information between RNM and HLR,which includes location of the mobile phone, current number of thesubscriber, and current subscriber location/routing information.

When the region/network where the mobile phone changes, the HLR informsRNM of the location update of the subscriber's mobile phone; the RNMdetermines whether to allocate a new number in the roamingregion/network for the mobile phone and cancel the number that has beenpreviously allocated in the roaming region/network according to thecurrent location of the mobile phone.

When the mobile phone initiates a call with the subscriber's number inthe roaming region, the RNM receives a route query, then accesses theHLR serving the subscriber corresponding to the number in the roamingregion, and obtains the subscriber's routing information, and returnsthe routing information to the query initiator;

The signaling employed by the interface is an extension to MAP (MobileApplication Part).

Above RNM addressing scheme has the following advantages:

First, it improves structural flexibility of cellular mobilecommunication network, i.e., a RNM can provide service for a pluralityof HLRs, and one HLR can obtain service from different RNMs depending onthe roaming region into which the subscriber is roaming, becausesubscribers, for which the localized roaming services are provided, maybe distributed in different HLRs instead of converging in one HLR, inparticular in the case of a large-scale network. In addition, the mobilephone numbers in different roaming regions/networks may be managed bydifferent RNMs;

Second, it ensures security of subscriber data in the home network:since the GMSC in the roaming region can't access the HLRs in the homeregion directly but has to access the HLRs through the RNM in the homeregion and can only obtain the data of a part of subscribers in the HLR(subscribers who subscribes to localized roaming service), RNM canprotect HLRs against unauthorized intrusion;

Third, the RNM is addressed through route query according to the numbersin the roaming region; thus this method avoids addressing to differentHLRs and simplifies the modification of data configuration in thenetwork. Since the subscribers in the network are distributed indifferent HLRs, if the contracted roaming phone numbers are allocated tothe respective HLRs, the volume of signaling route configuration datadescribed in step 2 will be increased drastically as signaling pathsgrow, especially when the signaling paths involve a plurality ofsignaling devices in the contracted roaming region/network and the homenetwork, causing severe degradation of operability;

Forth, since some number in a roaming region is managed in aconcentrated manner in RNM and shared by different subscribers in HLR,the utilization rate of the numbers is improved, the quantity ofrequired numbers in the roaming region is decreased, and thus theinterfaces between HLR and RNM are simplified. Since the subscribers inthe network are distributed in different HLRs, if the contracted roamingnumbers are allocated to the HLRs, the utilization rate of the numberswill be degraded, and more contracted roaming phone numbers arerequired.

Step 4: the subscriber utilizes the configuration of entities in thecontracted roaming region/network and that in the home network todevelop communication services in the roaming region/network; thus,localized roaming for the subscriber is implemented, the details are asfollows:

1. Subscriber location update process:

The embodiment of subscriber location update process is shown in FIG. 7;wherein an RNM (N) is a RNM corresponding to the current subscriberlocation/network; whereas an RNM (0) is a RNM corresponding to the oldsubscriber location/network (before location update). During thelocation update process, the HLR informs the old. VLR to delete the dataof the subscriber; as a well-known flow, it is not shown in the Figure;the procedures include:

The VLR at which the subscriber is registered currently sends a locationupdate request “Update Location” to the HLR in the subscriber's homeregion;

2) According to the current location of the subscriber, HLR informs RNM(N) of the subscriber location update via a “Location Change” message,which shall carry at least the following messages:

Subscriber identifier: e.g., International Mobile Subscriber identifier(IMSI) and/or the subscriber's mobile phone number N in the home region;

current location of the subscriber: “current location”;

old location of the subscriber: “old location”;

3) When receiving the “Location Change” message, the RNM (N) instructsthe current default number of the subscriber to HLR via a “NumberActivation” message, the parameter of which is number indicator N′. Ifthe RNM (N) has allocated a number to the subscriber (or the subscriberhas a bound number in the roaming region/network), then N′ is the numberin the roaming region/network; if the RNM (N) can't allocate a number inthe roaming region/network to the subscriber, then N′ indicates the HLRthat the current default number of the subscriber is the number N in thehome region (N′ may not be N but a contracted special number, becausethe RNM may be unable to obtain the subscriber's number in the homeregion); if the current location of the subscriber is in a roamingregion/network different to the old roaming region/network and the RNMhas allocated a mobile phone number in the old roaming region/networkfor the subscriber, the RNM will release that number (with the exceptionof number binding case);

4) the HLR inserts subscriber data in VLR utilizing a “Insert subscriberdata” message; wherein the subscriber's number is the current defaultnumber instructed by RNM (N);

5) The current VLR acknowledges insertion of subscriber data to the HLRin the home region utilizing a “Subscriber data insertion” message;

6) When receiving the acknowledgement for subscriber data insertion fromVLR, the HLR acknowledges the number allocation to RNM (N) utilizing a“Number activation ack” message; if the RNM (N) doesn't receive theacknowledgement from HLR for a certain period, it will release thenumber that has been allocated;

7) According to the old location, the HLR informs RNM (0) utilizing a“Cancel Location” message to indicate the subscriber has left; theparameters of the message include: subscriber identifier and “OldLocation”. If there is no binding relation between the local numberoccupied by the subscriber and the subscriber, the RNM (0) releases thenumber; the RNM (0) returns a “Cancel Location ack” message as aresponse to HLR; the parameter of the message is the subscriber'sidentifier;

8) The HLR returns an “Update location ack” message to VLR to confirmthe location update process has been finished;

Both the message in step 2) and the message in step 7) carry thesubscriber location information. This is necessary because a RNM maymanage the numbers in a plurality of different roaming regions and thusit has to determine which number should be allocated/released accordingto the subscriber location.

The subscriber identifier described in above steps refers to a numberthat is used to distinguish the subscriber and identify subscriberidentity, such as an IMSI or the subscriber's mobile phone number N inits home region.

Step 6) is carried out after step 5) is finished; thus, if sessioninterruption between HLR and VLR leads to failure of subscriber datainsertion, the RNM can't receive acknowledgement of number allocationfrom HLR, it will release the allocated number, thus avoiding numberoccupation in case of abnormalities.

2. The signaling flow of calling the subscriber with the subscribernumber N′ in the roaming region/network (as shown in FIG. 8):

1) When a call is initiated with the called subscriber's mobile phonenumber N′ in the roaming region/network, a GMSC in the network (usuallya GMSC in the roaming region/network) will initiate a route queryrequest to RNM;

2) When receiving the query request, the RNM finds the subscriberinformation according to the number in the roaming region, and send a“Send Routing Information” message with the subscriber identifier (IMSIor the number N in the home region) to query the HLR in the home regionabout the route;

3) the HLR sends a “Provide Roaming Number” message to VLR to request toallocate a roaming number; the request contains the subscriber's IMSI;

4) the VLR returns “Provide Roaming number ack” message to HLR toprovide the allocated roaming number MSRN;

5) the HLR returns a “Send Routing Information ack” message to RNM toprovide the route query result;

6) the RNM forwards the “Send Routing Information ack” message to theGMSC to provide route query acknowledgement, in order to instruct theroute for GMSC with the roaming number obtained from HLR;

3. The signaling flow of sending short messages to the subscriber'snumber N′ in the roaming region/network (as shown in FIG. 9)

The process through which short messages are submitted to the shortmessage service center is irrelevant to the present invention. TheFigure only illustrates the signaling flow of sending a short messagefrom the short message service center to mobile phone. The short messageservice center (SC) and SMS GMSC in the Figure may be in any network, aslong as the interface is compatible to the home network where thesubscriber is; the process through which SC issues a short message is asfollows:

1) The SC sends a short message to SMS GMSC, which initiates a routequery to RNM;

2) When receiving the query request, RNM queries about the subscriberinformation according to the number in the roaming region, and sends a“Send Routing Information for SM” message with subscriber identifier(IMSI or the number N in the home region) to the HLR in the home regionto query about the route;

3) The HLR sends a “Send Routing Information for SM ack” message to RNMto return the MSC number or SCSN number in the region where thesubscriber stays;

4) The RNM forwards the “Send Routing Information for SM ack” message toSMS GMSC as the acknowledgement for route query, to indicate the routefor the short message according to the MSC number or SGSN numberobtained from HLR;

5) The SMS GMSC sends the short message to the MSC or SGSN.

The present invention doesn't require any change to traditional servicefeatures in the mobile communication networks; neither does it affectthe traditional flows in the mobile communication networks. Taking thesignaling flow of calling the subscriber with the number N in the homecountry H as an example, this advantage will be described, referring toFIG. 10.

1) When a call is initiated with the called subscriber's mobile phonenumber N in the home region, a GMSC in the network (usually a GMSC inthe home network) initiates a route query request to HLR through a “SendRouting Information” message;

2) When receiving the query request, HLR sends a “Provide Roamingnumber” message to the VLR in the region where the subscriber is torequest to allocate a roaming number;

3) The VLR allocates a roaming number MSRN, and returns it to HLRthrough a “Provide Roaming number ack” message;

4) The HLR sends a route query acknowledgement to GMSC through a “SendRouting Information ACK” message, to instruct GMSC to establish callingroute with the roaming number MSRN;

Above process is the same as the process through which a mobilesubscriber in the traditional cellular mobile communication network iscalled; it will not be affected as more RNMs are added to the network.

FIG. 11 is the flow diagram of the second embodiment implemented withthe method of the present invention. In this embodiment, takingsubscriber roaming in a contracted roaming country and a non-contractedroaming country as an example, the present invention is furtherdescribed. For convenience, it is supposed that only one RNM is used inthe networks of each country.

As shown in FIG. 11, with the method described in the present invention,the roaming service operator needs to obtain some local mobile phonenumbers in other country for the international roaming service; thesecountries are called contracted roaming countries, the amount of therequired phone numbers in a contracted roaming country depends on thenumber of subscribers roaming in that country; the more the roamingsubscribers are, the more the numbers are required.

Please see FIG. 2, which is the structural diagram of a cellular mobilephone network implemented with the method of the present invention. FIG.2 illustrates the network devices related with the present invention andthe connections among the devices. As shown in the Figure, for the samesubscriber, number N is used in the home country, a local mobile phonenumber N1 is used in the contracted roaming country A, and the number Nin the home country is still used in the non-contracted roaming countryB.

When the present invention is implemented in a network shown in FIG. 2according to FIG. 11, the home country obtains the mobile phone numbersin the contracted roaming country first; when a mobile phone is roaming,in step A1, the mobile phone registers its location in the VLR in theroaming region through BTS, BSC and MSC because of change of mobilephone location; the VLR initiates a location update request to the HLRin the subscriber's home region. The HLR informs RNM of the subscriberlocation update and requests to allocate a mobile phone number in theroaming country to the mobile phone. In step A3, the RNM in the homecountry determines whether the roaming country is a contracted roamingcountry; if the subscriber is in a contracted roaming country, in stepA4, the RNM allocates a number from the available numbers in thecontracted roaming country and feeds it back to HLR, and stores themapping between the subscriber and the number (a plurality of numbersmay corresponds to the subscriber: the number in the home country, atemporary local number in the roaming region or bound numbers in othercontracted countries); if the subscriber is not in a contracted roamingcountry, in step A5, the RNM feeds the number in the home country backto HLR. The number fed back by RNM to HLR is called the current defaultnumber of the subscriber. In step A6, the HLR takes the number fed backby the RNM in the home country as the current default number of thesubscriber and inserts it along with other data in the VLR in the regionwhere the subscriber stays currently, deletes the subscriber's record inthe old VLR, and updates mobile phone location information in thesubscriber record; if the subscriber's current default number changes,the HLR will inform the subscriber of the new current default number fedback from the RNM in the subscriber's home region. In FIG. 2, when thesubscriber roams from the home country to the contracted roaming countryA, the RNM in the home country allocates a local mobile phone number N1to the subscriber; the HLR in the home country inserts number N1 andother subscriber data in the VLR in country A where the subscriber stayscurrently, deletes the subscriber record in the VLR in the home country;when the subscriber roams into a non-contracted roaming country B, theRNM instructs the subscriber's current default number is the number N inthe home country; the HLR in the home country inserts the number N andother subscriber data (e.g., contracted data) into the VLR in country Bwhere the subscriber stays currently.

On the basis of above steps, in step A7, when the subscriber receives anincoming call or initiates an outgoing call, the RNM will process thecall. That is to say, if the mobile phone of the roaming subscriber isthe caller, it uses the temporary roaming number allocated by RNM (i.e.,the current default mobile phone number) to initiate the call; if it isthe called, the caller may dial its local mobile phone number in theroaming country or its mobile phone number in the home country, and theMSC in the roaming country (if the caller dials the number in theroaming country) queries RNM or the MSC in the home country (if thecaller dials the number in the home country) queries HLR about thecalling route to the called subscriber. In the former case, the RNM mapsthe subscriber's number in roaming region to its number in home country,and then queries about HLR for the calling route. The HLR finds thecorresponding subscriber record and obtains subscriber locationinformation (i.e., VLR number in the current roaming country), and thusobtains the route information through accessing the VLR in the roamingcountry, and then instructs the MSC to establish the call. In the RNM inhome country, if any of the numbers maps to a subscriber, the mapping isunique; however, a subscriber may have been mapped to several numbers indifferent countries; no matter which number is dialed by the caller, aunique subscriber record can be found, and thus the subscriber locationinformation is obtained. In FIG. 2, when the subscriber roams intocountry A, the calling subscriber who calls the roaming subscriber maydial number N or N1.

In implementation of the embodiment shown in FIG. 11, only when thecountry after subscriber location change changes, the action ofallocating a mobile phone number in the roaming country will betriggered. As long as the subscriber stays in the country, above numberwill be used, until the subscriber leaves the country. After above phonenumber allocation process is finished, the network will inform theroaming subscriber of the temporary local number in the current roamingcountry by means of short message, voice or Unstructured SupplementaryService Data (USSD) or other ways, depending on the capability of thenetwork and the operator's choice.

When the mobile phone subscriber leaves the contracted roaming countryand enters into another country, the HLR in the home country will informthe RNM of the subscriber location update, the RNM will release thelocal mobile phone number occupied by the subscriber and break themapping between the number and the subscriber. The time span from thenumber is allocated to the time it is released is called the life timeof the number. For example, as shown in FIG. 2, when the roamingsubscriber leaves country A, the RNM will releases number N1.

In addition, in implementation of the embodiment shown in FIG. 12, toavoid possible conflict between phone numbers during dynamic allocation,certain anti-conflict policies may be used to reuse released numbers. Asimple but practicable policy is: the released number is lockedtemporarily within a certain time period, which is proportional to thelife time of the number; after the time period, the number may bereallocated to a roaming subscriber.

If a mobile phone subscriber frequently travels between the home countryand a contracted roaming country and requires to possess a number in thecontracted roaming country, a number may be allocated to the subscriberfrom the available numbers in the contracted roaming country as a fixednumber, which will not be allocated to any other roaming subscriber;even though the subscriber leaves the contracted roaming country, themapping between the number and the subscriber is still maintained. Aboveoperation is called number binding. When the subscriber roams into abovecontracted roaming country, the HLR in the home country is triggered bya location update request to request the RNM to allocate a local mobilephone number to the subscriber; the RNM will return the bound number toHLR, so that the subscriber is enabled to use the bound number toprocess calls. When the subscriber doesn't need the bound number anymore, the binding may be broken, and the number will be released andreused. Certainly, usually a plurality of numbers in the contractedroaming countries may be bound to a subscriber.

When the caller dials a bound number of the called subscriber, the RNMfinds the subscriber corresponding to that number, and queries HLR toobtain the subscriber location information (VLR number or MSC number),to accomplish route query. Therefore, if the called subscriber has boundnumbers, the caller will have more choices: the called subscriber'snumber in the home country, bound numbers, or the temporary number inthe current contracted roaming country.

Taking two roaming countries as an example, the embodiment in FIG. 11 isdescribed; actually, localized roaming service can be provided in aplurality of roaming countries, and the number of roaming countries isonly limited by the number of contracted countries contracted byoperators as well as storage capacity of and processing ability of theRNMs.

It should be noted that the network and method for implementinglocalized roaming of mobile subscribers provided by the presentinvention are universal; for example, the present invention can beapplied in domestic roaming regions as well as different cellular mobilecommunication systems including, but not limited to such systems as AMPS(Advanced Mobile Phone Service), GSM (Global System for MobileCommunications), D-AMPS (Digital-Advanced Mobile Phone Service), CDMA(Code Division Multiple Access), IMT-2000 (a generic term of thirdgeneration mobile communication systems defined by InternationalTelecommunication Union). If the mobile terminals support diverse airinterfaces (such as multi-mode terminals), the network and method canalso be used to provide roaming service among different systems.

1. A network for implementing localized roaming of mobile subscribers,comprising: a Visiting Location Register (VLR) in a contracted roamingnetwork, a Home Location Register (HLR) in a home network, and at leastone Roaming Number Manager (RNM) connected with the HLR in the homenetwork; wherein the HLR in the home network is adapted to inform an RNMcorresponding to the current location of a subscriber roaming in thecontracted roaming network of subscriber location update upon receivinga request from the VLR in the contracted roaming network; the RNM isadapted to allocate a local mobile phone number from a pool of localmobile phone numbers in the contracted roaming network for the phone,store mapping between the allocated local mobile phone number and thephone, and return the allocated local mobile phone number to the HLR inthe home network, wherein the allocated local mobile phone number forthe phone is adapted to be utilized as a calling number to make a callor as a called number to answer a call in the contracted roaming networkand released when the subscriber leaves the contracted roaming network;and the HLR in the home network is further adapted to send the localmobile phone number in the contracted roaming network to the VLR in thecontracted roaming network to be inserted in the VLR.
 2. The network forimplementing localized roaming of mobile subscribers according to claim1, wherein said RNM is embedded in said HLR.
 3. A method forimplementing localized roaming of mobile subscribers based on thenetwork of claim 1, comprising: a) configuring the RNM with local mobilephone numbers in the contracted roaming network, an independent PublicSwitched Telephone Network/Integrated Service Digital Network(PSTN/ISDN) number and a signaling point code; b) configuring data inentities of the contracted roaming network and entities of the homenetwork, so that the subscriber location query message taking a localnumber in the roaming network as the destination address will bedirected to the RNM in the home network; c) establishing interfacesbetween the RNM and entities of the contracted roaming network as wellas between the RNM and entities of the home network; d) developingcommunication services in the roaming network based on the configurationin respective entities of the contracted roaming network and the homenetwork, implementing localized roaming of the subscriber; wherein, theRNM is adapted to allocate a local mobile phone number from a pool oflocal mobile phone numbers in the contracted roaming network for thephone, wherein the allocated local mobile phone number for the phone isadapted to be utilized as a calling number to make a call or as a callednumber to answer a call in the contracted roaming network, and releasedwhen the subscriber leaves the contracted roaming network.
 4. The methodfor implementing localized roaming of mobile subscribers according toclaim 3, wherein said step c comprises: c1) establishing an interfacebetween the RNM and an MSC in the roaming network; c2) establishing aninterface between the RNM and the HLR in the home network.
 5. The methodfor implementing localized roaming of mobile subscribers according toclaim 3, wherein said step d comprises a subscriber location updateprocess: sending a location update request from the VLR currentlyserving the subscriber to the HLR in the home network; d2) according tothe location update request received from the VLR and the currentlocation of the subscriber, addressing the RNM corresponding to thecurrent location of the subscriber through the PSTN/ISDN number of RNMand informing the RNM of the subscriber location update, by the HLR inthe home network; d3) allocating by the RNM a local mobile phone numberin the roaming network, to the phone, and returning said number to theHLR in the home network; d4) inserting said local mobile phone number inthe roaming network into the VLR currently serving the subscriber, andreturning an acknowledgement message of obtaining said number in theroaming network to the RNM, by the HLR in the home network.
 6. Themethod for implementing localized roaming of mobile subscribersaccording to claim 5, wherein step d3, before allocating a local mobilephone number to the phone, further comprises: determining by the RNMwhether the roaming region where the subscriber is roaming is acontracted roaming region; if so, allocating one from the availablenumbers in the contracted roaming network and feeding the allocatednumber back to HLR in the home network by the RNM; otherwise feeding themobile phone number of the subscriber in the home network to HLR in thehome network.
 7. The method for implementing localized roaming of mobilesubscribers according to claim 6, wherein: an incoming call or anoutgoing call is processed by using the number fed back from RNM in thehome network.
 8. The method for implementing localized roaming of mobilesubscribers according to claim 7, wherein the call is processed by usingthe number fed back from RNM in the home network in the followingmanner: when acting as the caller, the subscriber uses the number fedback from the RNM in the home network to initiate a call; when thesubscriber acts as the called party, if the called number is the mobilephone number in home network, the MSC in the home network queries HLR inthe home network to determine the calling route, the HLR finds thecorresponding subscriber record, obtains address of VLR currentlyserving the subscriber, and accesses said VLR to obtain the callingroute, with which the HLR instructs the MSC in the home network toestablish a calling route; if the called number is a local mobile phonenumber in a roaming region, the MSC in the roaming network queries RNMabout calling route information, the RNM finds the subscriberidentifier, queries the HLR about the calling route information inaccordance with the subscriber identifier, and forwards the callingroute information returned from HLR to the MSC in the roaming network.9. The method for implementing localized roaming of mobile subscribersaccording to claim 5, further comprising: informing the subscriber ofthe location update by voice, short message or UnstructuredSupplementary Service Data.
 10. The method for implementing localizedroaming of mobile subscribers according to claim 5, further comprising:when the subscriber leaves the contracted roaming network, the HLR inthe home network informs the RNM of the subscriber location update, theRNM releases the local mobile phone number, occupied by the subscriber,in the roaming network, and breaks the mapping between the number andthe subscriber.
 11. The method for implementing localized roaming ofmobile subscribers according to claim 10, further comprising: bindingthe local mobile phone number in the contracted roaming network to a thesubscriber.
 12. The method for implementing localized roaming of mobilesubscribers according to claim 5, wherein said VLR in step addresses theHLR in the home network in accordance with International MobileSubscriber Identifier (IMSI) of the subscriber.
 13. The method forimplementing localized roaming of mobile subscribers according to claim5, wherein the information carried in the location update request sentfrom VLR to HLR in step and the parameters carried in the locationupdate informed from HLR to RNM in step d2 comprise: the IMSI of thesubscriber and/or the mobile phone number in the home network, currentlocation of the subscriber and old location of the subscriber.
 14. Themethod for implementing localized roaming of mobile subscribersaccording to claim 5, wherein the subscriber location update processfurther comprises: d5) informing the RNM serving the old location of thesubscriber by the HLR in the home region; d6) if there is no bindingrelation between the subscriber and the local mobile phone numberoccupied by the subscriber, releasing said local mobile phone numberoccupied by the subscriber by the RNM; and d7) sending a response fromthe RNM to the HLR in the home network.
 15. The method for implementinglocalized roaming of mobile subscribers according to claim 5, whereinthe subscriber location update process further comprises: sending anacknowledgement for number allocation from the HLR to the RNM servingthe current location of the subscriber, after receiving anacknowledgement for subscriber data insertion from the VLR.
 16. Themethod for implementing localized roaming of mobile subscribersaccording to claim 5, wherein the subscriber location update processfurther comprises: if not receiving the acknowledgement for numberallocation from the HLR for a determined period, the RNM releasing theallocated number.
 17. The method for implementing localized roaming ofmobile subscribers according to claim 3, wherein said step d comprises aprocess for calling the subscriber with the local mobile phone number inthe roaming region; said process comprising: d8) when the call is madeto the subscriber with the local mobile phone number in the roamingnetwork, initiating a route query from a GMSC in the roaming network tothe RNM currently serving the subscriber; d9) after receiving the query,the RNM searching for the subscriber identifier according to the localmobile phone number in the roaming network, and querying HLR in homenetwork about the calling route in accordance with the subscriberidentifier; d10) returning the query result from the HLR in the homenetwork to the RNM, which sends an acknowledgement for route query tothe GMSC and instructs the GMSC to establish the route with the numberobtained from the HLR.
 18. The method for implementing localized roamingof mobile subscribers according to claim 3, wherein said step d alsocomprises a process for calling the subscriber with the mobile phonenumber in the home network; said process comprising: d11) when the callis made to the subscriber by using the mobile phone number in the homenetwork, initiating a route query from a GMSC in the home network to theHLR in the home network; d12) after receiving the query, requesting theVLR currently serving the subscriber to allocate a temporary routingnumber according to the mobile phone number of the subscriber in thehome network by the HLR in the home network; d13) allocating, by the VLRcurrently serving the subscriber, a temporary routing number to thesubscriber, and returning said temporary routing number to the HLR inthe home network; d14) sending an acknowledgement for route query fromthe HLR in the home network to the GMSC in the home network, andinstructing the GMSC to establish a route with the allocated temporaryrouting number.
 19. The method for implementing localized roaming ofmobile subscribers according to claim 3, wherein said step d furthercomprises a process of sending a short message to the subscriber withthe local mobile phone number in the roaming network; said processcomprising: d15) sending a short message from a Short Message ServiceCenter (SC) to a Short Message Service Gateway Mobile Switching CenterSMS (GMSC), which initiates a route query to the RNM; d16) on receivingthe query searching for the subscriber identifier according to the localmobile phone number in the roaming network, and querying the HLR in thehome network about the route with the subscriber identifier, by the RNM;d17) returning the MSC number or a Service GPRS Supporting Node (SGSN)number currently serving the subscriber from the HLR in the home networkto the RNM; d18) sending an acknowledgement for route query from the RNMto the SMS GMSC, to instruct the route for the short message with theMSC number or the SGSN number obtained from the HLR in the home network,and issuing the short message by the SMS GMSC.